In connection with so-called jump-lifts, an elevator is taken into use already before the full length of the elevator hoistway has been completed. The elevator car moving in the bottom part of the elevator hoistway is supported and moved during the construction-time use suspended on ropes that are supported by a supporting structure in the elevator hoistway, which ropes are moved directly or indirectly with a hoisting machine. The top part of the elevator hoistway above the supporting structure is constructed at the same time as an elevator car moving in the already completed bottom part of the elevator hoistway serves people on the lower floors of the building. The hoisting machine can be supported e.g. on the aforementioned supporting structure. When the part of the elevator hoistway under construction above the supporting platform has reached a sufficient stage of readiness, it can be taken into use. In this case a lift (a so-called jump-lift) is performed, wherein the supporting structure is raised to a higher position in the elevator hoistway, thus extending the service range of the elevator car upwards. A worksite crane in use in the construction of the building can, for example, be used for the lifting. Alternatively, the supporting structure could be shifted with a hoist, which is supported on a support structure to be arranged in the hoistway above the machine room platform. When the elevator hoistway has reached its final height, the elevator is left permanently in its position, possibly however first performing some conversion procedures, e.g. by removing the elements required for jump-lifts, possibly by replacing the roping and/or by changing its route. One solution according to prior art is described in publications WO 2010100319 A1 and WO 2011048255 A1.
For enabling jump-lifts, choices have had to be made in the placement of the supporting structure and of the ropes hanging supported by it, as well as in the placement of the components that are in connection with the supporting structure, which choices differ from the component placement of a conventional elevator. For example, enabling the movability of the supporting structure has required a support means system, which takes space to a degree that reduces the freedom of placement of the other components. Likewise, enabling an increase in the length of the ropes has had to be taken into account. Generally the ropes are led to a rope supply storage via an openable clamp that is in connection with the supporting structure. Generally, there has further been a need to form the layout in such a way that safe working on the supporting structure is made possible. In addition, it has been necessary to dispose a system of means in connection with the supporting structure for moving the supporting structure. Taking into account the many exceptional issues that must be addressed has hampered the locating of the center of mass of the supporting structure in the best possible spot from the viewpoint of a jump-lift. It has been noticed that the location of the center of mass during a jump-lift is of great importance to dividing the support forces of the supporting structure when the supporting structure is supported in its position in the hoistway. Likewise, the location of the center of mass during a jump-lift is of great importance to dividing the support forces of the supporting structure during the jump-lift. Problems have also been caused by, inter alia, the fact that if the center of mass is at a distance from the center point of the hoistway, the support forces of the hoisting arrangement must also be received in the same manner eccentrically, which can impede the finding of a support point, especially in solutions in which the hoisting arrangement rests on structures of the hoistway. The location of the center of mass also otherwise affects control of the lifting of the supporting structure. The location of the center of mass affects e.g. the susceptibility of the supporting structure to lurching by affecting the lever arm lengths of the forces acting on the edge areas of the supporting structure. One factor significantly affecting the location of the center of mass is the route traveled by the ropes and the location of the rope pulley diverting the roping that is in connection with the supporting structure, which rope pulley is generally a rope pulley of the hoisting machine. During the lifting of the supporting structure, the weight of the ropes hanging supported by the supporting structure is large, in which case the effect of them on the center of mass is also great. In addition, the self-weight of the rope pulley and of a machine possibly connected to it affect the center of mass. The placement of these heavyweight structures has been difficult to implement advantageously from the viewpoint of the center of mass, which has resulted in either an eccentric center of mass or in an otherwise complex structure. Problems relating to this have arisen in particular when the elevator units are supported with roping that travels via the rope pulleys of an elevator unit. Yet another problem has been that at the end of the fabrication process of an elevator, when the elevator is converted into the final elevator, the exceptional layout during the jump-lift has generally had to be drastically changed. For example, it has often been necessary to change the location of the aforementioned rope pulley of the supporting structure. More particularly, it has been necessary to change the location of the rope pulley when it has been desired to change the suspension of the final elevator car and/or counterweight from a 2:1 lifting ratio to a 1:1 lifting ratio. A corresponding problem has become evident when changing the suspension of the compensating ropes hanging suspended from the elevator car and the counterweight.